JPS62158583A - Production of rolled clad steel sheet - Google Patents

Abstract

PURPOSE:To obtain a clad steel having high joint strength without oxidation by hermetically sealing a cladding metal with a covering steel sheet contg. carbon at a specific ratio, holding such cladding metal in place between a base metal and camber preventive material, heating the assembly to a specific temp. and joining the same by rolling. CONSTITUTION:The cladding metal 1 is hermetically sealed by the covering steel sheet 3 contg. <=0.03% carbon and is held in place in a laminar state between the base metal 6 which is a steel and the camber preventive material 7. A separating agent 8 is interposed between the steel sheet 3 and the material 7. A distance piece 9 is provided to prevent the failure of the steel sheet 3 in the stage of welding the four peripheries of the material 7. The base metal 6 and the material 7 are welded. Such stock assembly is heated to >=650 deg.C and <=900 deg.C and is subjected to hot rolling, the periphery of the rolling material is cut to separate the material. The covering sheet on the outside of the cladding metal is removed. The clad steel having the high joint strength is thus obtd. without oxidizing the cladding metal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a cladding material by rolling, and in particular to assembly, rolling, and finishing of a cladding material.

(Prior art) All of the methods for producing cladding materials described in Japanese Patent Application Laid-Open Nos. 55-100890, 55-128390, 56-122681, and 57-109587 as prior art. They are layered in the order of base material, cladding material, laminate material, and base material in a sandwich-like order, or covering material, laminate material, and base material in this order. There is a high possibility that the surface to be joined will be contaminated. Furthermore, in the method described in JP-A-57-115991, a separator is hermetically welded between the laminates, but if the welded part breaks due to rolling force, the separator will be on the same surface as the surface to be joined. Since the separating agent is included in the space, there is a high possibility that the separating agent will contaminate the surface to be joined.
The method described in Japanese Patent No. 154387 involves welding the air vent hole after extruding residual air from the air vent hole by cold rolling, but since a cold rolling step is added, there is a high possibility that manufacturing costs will increase.

In addition, in conventional technology, when metals that tend to generate carbides such as titanium, zirconium, and chromium are used as laminates, steel with a carbon content of 0.12% or more coexists in the space where the laminates exist, and when these are heated, The carbon in the steel forms carbides with the laminate on the surface of the laminate, which adversely affects the bending process and shear strength of the product. This tendency is significantly increased when organic matter is present in the space where the laminate is present.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for manufacturing clad steel that has strong joint strength and has small warpage during and after rolling.

(Means for solving problems) The gist of the present invention is as follows.

(1) The laminated material is sealed with a cover steel plate having a carbon content of 0.03% or less, and the cover steel plate assembly containing the laminated material is sandwiched between the steel base material and the warpage prevention material in a layered manner. After welding the material and the anti-warpage material, the material is heated to a temperature of 650°C or more and 900°C or less and hot-rolled.The periphery of the thus obtained rolled material is cut and separated at the separating agent position, and the outer surface of the laminated material is covered. A method for producing a rolled clad steel plate of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel, characterized by removing the steel plate.

(2) Surround the laminate with a cover steel plate with a carbon content of 0.03% or less, weld the four circumferences of the cover steel plate while blowing inert gas into the inside, and heat the cover steel plate surface to 100℃ or higher. After reducing the pressure of the space containing the laminated material to 10 torr or less and sealing it, the covered steel plate assembly is sandwiched between the steel base material and the warpage prevention material in a layered manner, and the steel base material and the warpage prevention material are welded. The rolled material is heated to 650°C or more and 900°C or less and hot-rolled, the periphery of the thus obtained rolled material is cut and separated at the separating agent position, and the covering steel plate on the outer surface of the laminated material is removed by cutting, grinding, or pickling. A method for producing a rolled clad steel plate made of titanium, titanium alloy, zirconium, zirconium alloy or chromium-containing steel, characterized in that:

(3) The laminated material is sealed with a cover steel plate having a carbon content of 0.03% or less, and the cover steel plate assembly containing the laminated material is sandwiched between the steel base material and the warpage prevention material in a layered manner. After welding the material and the anti-warp material, the material is heated to a temperature of 650°C or more and 900°C or less, hot rolled, the periphery of the thus obtained rolled material is cut and separated at the separating agent position, and then the laminated material is prepared. A method for producing a rolled clad steel plate of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel, which comprises reheating and hot rolling with a covering steel plate attached to the outer surface.

(Operation of the invention) The basic constituent elements of the present invention and their operation can be summarized as follows.

(1) In the present invention, the laminated material is sealed with a covering steel plate having a carbon content of 0.03q6 or less to isolate the steel base material having a high carbon content. This requirement makes the carbon content of the steel base material independent of carbide formation in the laminate, making it possible to increase the carbon content of the steel base material to increase its strength. Carbon steel, which does not contain alloying elements, is most suitable for this covering steel plate because it is cheap and easy to process, but carbon steel with a carbon content of 0.
Steel containing alloying elements can be used if the content is 0.3% or less.

Further, the thickness of the covering steel plate is preferably 0.1 W or more in view of the strength of the plate during material assembly and the diffusion distance of carbon during rolling, and so-called foil is inappropriate.

(2) In the present invention, by heating the material assembly to 900°C or less and rolling joining it, carbon in the cover steel plate is prevented from moving to the laminate material during heating and forming carbides with the laminate material. . When the heating temperature exceeds 900° C., carbonization of the clad metal becomes noticeable due to the release of carbon or carbide from the cladding steel plate, and the bending or shearing properties of the clad steel product begin to deteriorate. Further, the heating temperature is desirably higher than the recrystallization temperature of the material, that is, 650°C.

(3) In the present invention, the surface of the covering steel plate that seals the laminate is
By heating the space above 00°C and reducing the pressure to below 10'' torr and sealing the space formed by the laminated material and covering steel plate, organic matter is removed from this space and the decrease in carbon supply is minimized. , it is possible to reduce the amount of carbide produced in the laminate.

(4) In the present invention, the cladding material is further fixed to the base material by a covering steel plate, and the surrounding steel plate is also firmly welded and fixed to the base material, thereby preventing displacement of the cladding material during the processing process, breakage of the covering steel plate, etc. Furthermore, it is possible to prevent deterioration in the dimensional accuracy of the laminate due to non-uniform deformation.

In order to maximize these effects, the contact surface between the covering steel plate and the laminate used in the present invention is also kept sufficiently clean for the purpose of bonding, and the space where the laminate is present is free of any components that may impede bonding. Eliminate to the extent industrially possible. By doing this, both sides of the laminate are completely joined and rolled while being sufficiently constrained, thereby preventing warping and making deformation uniform.

(5) In the present invention, it is desirable to assemble the materials as follows. In other words, the base material, the cladding material, and the covering steel plate are stacked in layers with their mating surfaces cleaned, and when welding the periphery of the base material and the covering steel plate, an inert gas such as argon or helium is applied between the base material and the covering steel plate. By sealingly welding the base metal and the covering steel plate while injecting ivy, welding hume,
Or to prevent internal contamination due to welding heat.

(6) When a warpage prevention material is used in the present invention, it is necessary that the warpage prevention material and the contacting covering steel plate can be easily separated after hot rolling. For this purpose, an oxide layer with a thickness of 30 μm or more should be present on at least one of these contacting surfaces, or ht203.8102. T
A powder containing one or more of iO2, Cr2O, Fe2O, Fa, and 04 as a main component is applied to a thickness of 10 μm or more using a resin as a vehicle. The reason why a resin is used as a vehicle is that it is inexpensive and has excellent paintability, but since it generates a large amount of gas during heating, it is desirable that the surface to be separated is communicated with the outside air to exhaust this gas.

Next, a method of assembling the materials used in the present invention and its structure will be explained.

FIG. 1 shows an intermediate state of a material assembly for implementing the present invention. The cleaned cladding material 1 is layered with a G steel plate 2.3 whose surface in contact with the cladding material is cleaned, and the four circumferences of the covering steel plates are welded to seal the laminate material. At this time, in order to prevent the cladding material 1 and the covering steel plate 2.3 for the cladding material from being contaminated by heat, sludge, or ivy during welding, the nozzle 4 is heated using an inert gas such as argon or helium, or a non-containing gas such as nitrogen or carbon dioxide gas. It is preferable to blow in oxidizing gas. After welding the four circumferences of the cover steel plate, the nozzle 4 is closed, but before that, while heating the cover steel plate surface to 100°C or higher, the space formed by the laminate and the cover steel plate is depressurized to a pressure of 10-' torr or less. It is desirable to do so.

Heating the surface of the covered steel plate is effective in eliminating moisture and organic matter, and reducing the pressure is effective in eliminating moisture and organic matter even more efficiently and preventing oxidation of the surfaces to be joined. The timing of welding the cover steel plate and the base metal is not particularly limited, but after welding the four circumferences of the cover steel plate as shown in Fig. 1, weld the cover steel plate and the base metal 6 as shown in Fig. 2. is the easiest to work with, and also keeps the surface to be joined clean.

FIG. 3 is a sectional view of the completed material assembly, in which a separating agent 8 is interposed between the covering steel plate 2 and the anti-warp material 7.

This separating agent can be used by pre-forming an oxide layer of 30 μm or more on the outer surface of the covering steel plate 2 or the surface of the anti-warping material 7 that is in contact with it, or
0. , 8102. TiC2, Cr2O,.

It is preferable that a powder containing one or more of Fe2O, Fe, and 04 as a main component is coated and dried to a thickness of 10 μm or more using a resin as a vehicle. The distance piece 9 is used when welding the four circumferences of the base material 6 and the anti-warp material 7 to the covering steel plate 2.
function so as not to be damaged. If a separating agent 8 is interposed between the distance piece 9 and the base material or anti-warp material to prevent them from joining, if the distance piece 9 is cut after rolling, the laminate material will be exposed to the atmosphere. The anti-warpage material can be removed without exposing it to the surface. Even if the cladding material from which the anti-warpage material has been removed is reheated as it is, the cladding material l will be completely prevented from oxidizing by the covering steel plate 2, and the cladding material will not be directly damaged by the rolls during subsequent rolling. do not have. The covering steel plate on the outer surface of the laminate is removed by cutting, grinding or pickling.

The anti-warpage member 7 can be assembled as shown in FIG. That is, the two assemblies shown in FIG. 2 are assembled by welding the four circumferences of the two assemblies shown in FIG. 4 so that the cover steel plates 2 face each other with the separating material in between. From such a material assembly, 2
Several clad steel plates can be manufactured at one time.

(Example) Table 1 shows examples. The steel base material used was 0.17% carbon steel, and the cover steel material used 0.01% ultra-low carbon steel. Assembly material is width 1
Although it is a small test piece with a length of 5.0 m and a length of 200 m, it is possible to sufficiently evaluate the rolling condition and quality for production rolling. All test pieces were welded by MIG welding, and argon gas was blown into the interior to prevent welding contamination during welding, and after welding was completed, the interior was depressurized to 1O-2 torr. The heating temperature was 800°C in all cases.

In Example 1 of the conventional method, a 6 inch thick stainless steel is directly connected to a 20 m5 thick steel base material. In this example, there is a large warpage toward the stainless steel side during rolling, and the warpage increases after cooling, and the thickness deviation of the laminate (: maximum thickness - minimum thickness) is 0.
．． It is thick at 33m. The shear strength is low and the bending test results are also poor.

In example 2 of the conventional method, the covered steel plates 2.2' and 3°3' are shown in Figure 4.
However, the shear strength is low and the side bending test results are also poor.

Examples 3 and 4 of the present invention have the structures shown in FIGS. 3 and 4, respectively, and are asymmetrical structures to make warpage more noticeable, but the warpage during rolling and cooling is within a sufficiently permissible range. It is in. Furthermore, the thickness deviation of the laminated material, the shear strength of the base material and the laminated material, the side bending test, and the test results are all good. The shear strength and side bending test results are related to the distribution thickness of carbides enriched near the joint boundary. Carbide is mainly TlC1 when the cladding material is titanium or titanium alloy, or Cr when the covering steel plate is stainless steel.
7C5e Cr23C6. These carbons and compounds were analyzed by line analysis using an EPMA (model name: am-8M) made by Koguruma Seisakusho, with an accelerating voltage of 20 kV, a sample current of 0.01 μA, and a beam diameter of 1 μm, crossing the cross section of the joint at right angles. In this case, when the count number 0.5k is the full width of the recording paper, the carbon concentration distance at the bonding boundary is measured as shown in FIG. This carbon am distance has a relationship with shear strength, and in the example of titanium clad steel, as shown in Figure 6, JI
Shear value specified by SG 3603 14 kg f /I
m2 can be satisfied if the carbon concentration distance is 20 μm or less. Such concentration of carbon at the bond boundary between titanium and steel is Tic, and if it is in a small amount, it improves the shear strength, but if TiC is generated to the extent that the carbon concentration distance exceeds 20 μm, it will actually weaken the carbon concentration. Some new low values are mixed. The above is the same when stainless steel is used as a laminated material or as an intermediate material, and in this case, Cr7C3 and Cr23C6 are generated in the same way instead of Tic and exhibit the same behavior.

(Effects of the Invention) According to the present invention, clad steel with strong bonding strength can be manufactured without oxidizing expensive laminate materials.

In the present invention, the covering material is a steel plate with a carbon content of 0.03 or less, and the bonding material is titanium or its alloy, zirconium,
Metals such as stainless steel that tend to form carbides. According to the present invention, assembly and welding of materials is also easy and inexpensive. Furthermore, steel with a carbon content of 0.12% or more, whose shear test value conventionally fluctuated to a low level, is used as the base material, and the shear test value can be stabilized at a high level.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing an intermediate stage of assembling the rolling material of the present invention, Figures 3 and 4 are diagrams showing the state of the rolling material of the present invention after assembly, and Figure 5 is carbon enrichment. An explanatory diagram of distance, FIG. 6 is a diagram showing the relationship between carbon concentration distance and shear strength, which shows the effect of the present invention. 1: Laminating material, 2.3: Covering steel plate, 4: Nozzle, 5: Base material side of covering steel plate, 6: Base material, 7 2 Warpage prevention material, 8: Min.1
11J, 9: Distance piece, 10: Four-circumference weld.

Claims (3)

[Claims] (1) The laminated material is sealed with a cover steel plate having a carbon content of 0.03% or less, and the cover steel plate assembly containing the laminated material is sandwiched between the steel base material and the warpage prevention material in a layered manner. After welding the material and the anti-warpage material, the material is heated to a temperature of 650°C or more and 900°C or less and hot-rolled.The periphery of the thus obtained rolled material is cut and separated at the separating agent position, and the outer surface of the laminated material is covered. A method for producing a rolled clad steel plate of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel, characterized by removing the steel plate. (2) Surround the laminate with a cover steel plate with a carbon content of 0.03% or less, weld the four circumferences of the cover steel plate while blowing inert gas into the inside, and heat the cover steel plate surface to 100℃ or higher. The space including the laminated material is 10^-^1 torr.
The cover steel plate assembly is sandwiched between the steel base material and the warpage prevention material in a layered manner, and the steel base material and warpage prevention material are welded and then heated to a temperature of 650°C or more and 900°C or less. titanium, which is characterized by hot rolling, cutting the periphery of the thus obtained rolled material, separating it at the separating agent position, and removing the covering steel plate on the outer surface of the laminated material by cutting, grinding or pickling. Process for producing rolled clad steel sheets made of alloy, zirconium, zirconium alloy or chromium-containing steel. (3) The laminated material is sealed with a cover steel plate having a carbon content of 0.03% or less, and the cover steel plate assembly containing the laminated material is sandwiched between the steel base material and the warpage prevention material in a layered manner. After welding the material and the anti-warping material, the material is heated to a temperature above 650°C and below 900°C and hot rolled, the periphery of the thus obtained rolled material is cut and separated at the separating agent position, and then the outer surface of the laminate is A method for producing a rolled clad steel plate of titanium, titanium alloy, zirconium, zirconium alloy, or chromium-containing steel, comprising reheating and hot rolling with the covering steel plate attached.